The prior art is replete with attempts to allow independent rotation of oppositely disposed railway car wheels which are oppositely disposed on the opposite ends of an axle. For example in one early illustration, applicant is aware of U.S. Pat. No. 12,572, which issued Mar. 20, 1855 to Prentiss for a Car Axle. More particularly however applicant is aware of prior art having the specific object of providing a segmented axle extending between oppositely disposed railway car wheels for the purpose of permitting free rotation of one axle section relative to the other axle section when travelling around curves as for example stated in U.S. Pat. No. 977,002 which issued Nov. 29, 1910 to Girt et al for an Independent Car Axle, or so as to allow the wheels to operate independently of each other to thereby reduce the friction when the car is going around a curve and so that the outer wheel can revolve faster than the inner one, as taught in U.S. Pat. No. 205,324 which issued Jun. 25, 1878 to Whittic for a Car-Axel, or so as to reduce friction and consequent wear of car wheels and track when passing around a curve as taught in U.S. Pat. No. 302,120 which issued Jul. 15, 1884 to Fleming for a Car Axel, or, so as to provide car axles which permit their two wheels to turn independently of each other by the insertion of two separate short axles into opposite ends of a long sleeve or tube which connects the short axles and holds them in line as taught in U.S. Pat. No. 134,247 which issued Dec. 24, 1872 to Braymer et al for Car-Axles.
Applicant is also aware of a paper by John A. Elkins dated September, 1988, entitled Independently Rotating Wheels: A Simple Modification to Improve the Performance of the Conventional Three-Piece Truck; 9th International Wheelset Congress.
What is neither taught nor suggested in the prior art and which is an object of the present invention to provide is a simple load and bending moment resistant arrangement of independent axle sections, in one embodiment lockable, which advantageously may be retrofit into existing one-piece axles, for use on the style of railway cars where the load is applied on the transversely outward side of the wheels so as to apply an upward bending moment urging the centre of the axle upwardly, and in particular for use on railway truck wheel and axle sets as disclosed by way of example in U.S. Pat. No. 3,802,352 which issued to The Timken Company on Apr. 9, 1974 for the invention of Keller. A copy of FIG. 1 from the Keller patent forms the prior art FIG. 1 of the present specification.
By way of illustration of the problem that is addressed by the present invention, in applicant's experience, conventional car axle housings, bushings and bearings are designed to carry in the order of 230,000 lbs between four axles under a car and that these loads are distributed to the wheels by loads applied to conventional bearings mounted on the laterally outermost ends of car axles where the axles protrude from the corresponding pair of oppositely disposed wheels. Thus loads in the order of approximately 30,000 lbs bear down on each of the outermost ends of the conventional unitary axles thereby exerting a bending moment on both ends of the axles which urges the axles to bow upwardly into a curve. In a conventional axle the loads are substantially resisted by the use of steel axles having a significant cross-sectional diameter, in the order of approximately seven and eight inches in applicant's experience. It is thus advantageous to replicate the load and bending moment bearing capabilities of a conventional solid axle in a segmented axle which provides for independent rotation of the opposite wheels on each axle and which also advantageously may be retrofitted to existing conventional solid axles.